1. Field of the Invention
The present invention relates to a method of manufacturing an eyeglass lens, and more particularly, to a method of manufacturing an eyeglass lens comprising the step of creating an optical surface by polishing a non-optical surface of a semifinished lens.
2. Discussion of the Background
In the process of manufacturing an eyeglass lens, mass producing and storing a lens that is thicker than the finished dimension (a semifinished lens), and, when an order is received, finishing a product lens (a finished lens) having the desired optical characteristics based on the needs of the user is widely practiced. Usually, on a surface on the object side of the semifinished lens, a mold surface is transferred during casting polymerization to finish an optical surface. Additionally, on a surface on the eye side (concave surface), mechanical processing (grinding or cutting) is used to process a desired surface shape based on a lens prescription. However, when that is done, traces due to mechanical processing remain on the concave surface. Thus, use as an optical lens is precluded. Accordingly, polishing processing is usually conducted after the mechanical processing. This polishing processing makes it possible to obtain a finished lens with desired finished optical surfaces on both sides. Normally, a scratch-preventing protective film is adhered to the optical surface side in advance and this polishing processing is conducted in a state where the protective film surface is secured in a block jig (for example, see Japanese Unexamined Patent Publication (KOKAI) No. 2008-183714 and Japanese Patent No. 4084081 or English language family members US2003/129925A1, U.S. Pat. No. 6,932,678, US2005/227592A1, U.S. Pat. No. 7,144,305, US2006/073770A1, U.S. Pat. No. 7,189,148, US2007/202778A1, U.S. Pat. No. 7,500,903, which are expressly incorporated herein by reference in their entirety).
Conventional semifinished lenses are generally uncoated lenses without coatings on the optical surface side. By contrast, semifinished lenses with an optical surface on which a functional film has been formed have been manufactured in recent years. This has been done because, by forming a functional film, it is possible to prevent scratching and the adhesion of foreign matter to the optical surface during processing, as well as to prevent corrosion due to moisture and oxygen in the atmosphere. Further, when a functional film is previously formed on a lens that is in a semifinished state, there is no need to form the functional film upon receipt of an order. This is advantageous for reducing the time elapsing between the receipt of an order and shipment of the finished lens.
However, when the present inventor polished the non-optical surface of the semifinished lens on which a functional film had been applied, he determined that the lens could not be adequately secured during polishing, and that it was sometimes difficult to conduct polishing processing. When the present inventor conducted further research in this regard, they found that there was inadequate adhesion between the protective film and the functional film, and that an inability to withstand the load during polishing processing was why the lens could not be adequately secured during polishing.